The present invention relates to a log flaking and loading method and apparatus, particularly for producing four-sided cants from logs by cutting flakes or strands.
Wood flaking is a fundamental process in the production of wood products from raw logs. Particularly, flaking machines are used to produce a relatively smooth lumber finish on the log by cutting flakes therefrom. The flakes may be of bulk dimensions, or they may be produced in thin, wafer-like sheets, such as to be used in the production of oriented strand board ("OSB"), a wood product commonly employed as a substitute for plywood in which wafer-like "flakes or strands," typically about 0.020" thick, are pressed together and glued into sheet form. In such applications, it is desirable that the flakes or strands be strong and robust.
The flaking machines employ cutting heads of a variety of different configurations. Commonly, the cutting head is a rotating drum or disc carrying a plurality of knives around its circumference. The log is forced against the cutting head while the cutting head turns and which, thereby, cuts the flakes or strands. This produces flakes or strands that are not as strong and robust as is desirable.
The flaking machines are typically used to cut a substantially plane surface that is parallel to the elongate axis of the log. The portion of the log remaining after such cutting is termed a "cant." Where only one surface is cut, the cant is "one-sided." A "four-sided" cant is typically a finished or nearly finished piece of lumber, such as a 4.times.4 stud.
Particularly when producing lumber from logs of small diameter, it is desirable to process the log directly to form a four sided cant. It is most efficient to produce flakes or strands of sufficiently high quality for, e.g., OSB products in the same operation as that used to produce the four sided cant. It has not apparent, however, that this has been recognized in the prior art.
Four-sided cants are often produced by passing the log by a single cutting head four times. Such a method is time consuming, however. To increase throughput, a drum-style cutting head that is substantially as long as the length of log or other work piece being cut may be employed. The log is rotated slowly as the lathe head is rotated rapidly, the spacing between the lathe head and log being controlled by contact between a cam on the one and a cam follower on the other wherein the cam has the desired cross-sectional shape of the finished cant, See Peter Koch, "Development of the Shaping Lathe Headrig", U.S. Department of Agriculture Forest Service Research Paper SO-98 (1974), incorporated herein by reference in its entirety. While the concept of the shaping lathe headrig could be used to increase the speed of four sided cant production, this would remain limited by the requirement to "machine" all four sides of the log with a single cutting head.
Accordingly, there is a need for a log flaking and loading method and apparatus that provides for producing higher quality flakes or strands for use in wood products as a result of producing four sided cants, and for increasing the production speed of producing the four sided cants.